The relationship between obesity and primary total knee replacement: A scoping review of the literature

Abstract

Background

Primary Total Knee Replacement (TKR) is one of the most commonly performed elective orthopaedic procedures globally. Many of the patients undergoing this type of surgery are overweight or obese. In the UK clinical commissioning groups have imposed arbitrary Body Mass Index (BMI) thresholds for TKR surgery. Many obese patients undergoing TKR believe they will lose weight following the procedure because of increased mobility.

Aim

This paper aims to present the findings of a scoping literature review about the relationship between obesity and primary TKR and to make recommendations for clinical practice, education and policy

Methods

A scoping literature review investigated the impact of BMI/body weight on the need for TKR, the impact of body weight and or BMI on patient outcomes following TKR; weight loss/gain following TKR and the implications of obesity on cost of TKR.

Findings

Seventy-one papers were included in the review. Seven studies reported statistically significant associations between increased BMI/obesity with the need for TKR. Thirty of the studies reported worse outcomes for obese patients compared to non-obese comparators. Forty of the studies reported no difference between obese and non-obese participants including some where outcomes of obese patients were better than non-obese comparators. Eight studies reported on changes to weight before and after TKR, 3 of the studies reporting a higher percentage losing weight than gaining weight and 4 studies reported obese patients gained weight. The 8th study reported morbidly obese patients largely returned to their baseline BMI postoperatively.

Conclusion

The findings of the review challenge the legitimacy of setting BMI thresholds to control access to TKR surgery. There is an urgent need to develop evidence based approaches to support weight loss and weight management for this group of patients. Obese patients undergoing TKR should receive specific information regarding potential additional risk of complications and poorer outcomes. There is a need for health promotion regarding the association of being overweight/ obese in young adulthood and developing osteoarthritis of the knee joints requiring TKR in middle and older age.